Should I quit my internship?

I’m currently and intern for a small Web design company/ Social marketing firm I have just completed my first week at the company and I have to complete more than 120 hours to get credit from my college. The problem is that I’m not really learning anything and I feel more like a secretary than an intern my program is Business management but I have not done anything this week that has given me experience to learn how a business is run. The owner of this business recently went on vacation to Cancun so we only communicate by email. While’s he’s on vacation he want me to run errands to other business to pick up credit card information. Like I have said I’m more like his personal secretary than an intern. Also he wants me to keep him updated each day on the progress in the office I guess he wants me to keep an eye on everyone while he’s gone. It’s too late in the summer for me to find a new internship and I need to have this internship completed by 8/9/2011 to graduate on time with my degree any advice on what I should do? By the way this is an unpaid internship and he requires me to put in at least 30 hours a week at his company. The problem is that I work full time second shift for my real job so I intern in the morning and work in the afternoon I’m exhausted. Should I continue with this internship or try and find a new internship? I’m in Michigan.